actually, the US government could shutdown massive parts of the internet. they have the authority to do so. all they have to do is order all US isp's to cease and desist and abstain there services and order isp's to shutdown and close all foriegn company and buisness operations that they control and any subsidaries under there power. also closing any international network ports into this country.
this would shutdown atleast 90% if not more of the world network (aka the internet)
that kinda makes me proud of my country
to see who control IP's which control the communication of networks, please see:
www.arin.net (north america),
www.icann.org,
www.internic.net, .. i cant rember the one for asia, but owell
some more:
http://www.isoc.org/ http://www.iana.org/ http://www.ietf.org/ http://www.nanog.org/ http://www.aso.icann.org/ http://www.afrinic.net/ (africa)
http://www.apnic.net/ (asia)
http://www.lacnic.net/ (south america -latin america-)
http://www.ripe.net/ (europe)